1. Field of the Invention
The present invention relates generally to liquid handling apparatus. More particularly the invention concerns an improved liquid handling system for controllably dispensing, aspirating and intermixing various liquids through the use of a precision liquid metering and aspirating device having a fixed base and a rotatable fluid containing cartridge.
2. Discussion of the Prior Art
There exists in the prior art a wide variety of volumetric devices for dispensing and aspirating liquids such as reagents. On one end of the spectrum is the simple manual type, such as the pipette, wherein a quantity of liquid is sucked up into a graduated tube and then discharged as a metered quantity. On the other end of the spectrum are various highly sophisticated mechanical and electromechanical devices adapted to reproducably dispense precise quantities of liquid from conventional or specially designed reagent containers. The manual type devices often lack the necessary precision, while the mechanized devices frequently are unduly complex, extremely costly and, in many instances, tend to fail or malfunction in continuous use.
The apparatus disclosed in U.S. Letters Pat. Nos. 3,834,241 issued to Garren et al and in 4,054,061 issued to Valt are exemplary of manual type pipette devices.
The apparatus disclosed in U.S. Letters Pat. Nos. 3,931,915 issued to Downings et al and in 4,101,283 issued to Sundstrom are exemplary of mechanical and electromechanical dispensing devices. The latter mentioned Sundstrom device is specifically adapted for use in accurately pipetting specified digitally programmed volumes of sample and the delivery of likewise specified, digitally programmed, volumes of reagent. The thrust of the Sundstrom invention is directed toward the provision of a specially constructed plunger which is rotated within a non-threaded reagent container. Rotation of the plunger is controlled by a relatively sophisticated light-photo cell system which is operably interconnected with motor means through somewhat complex counting and connecting circuits. As a result of the particular configuration of the Sundstrom plunger, it cuts grooves in the inner wall of the reagent container as it rotates.
One of the most successful reagent metering and dispensing devices developed to date is described in the copending application Ser. No. 823,939 now Pat. No. 4,738,826 filed by the present inventor.
The apparatus of the present invention embodies, as a subassembly thereof, the device described in Ser. No. 823,939. As will be better understood from the description which follows, the apparatus of the present invention is extremely versatile and well suited for automatically performing liquid handling operations requiring the utmost precision. For example, the apparatus can be used for automated liquid sampling and analysis, for automated infusion of liquids to a patient via an access catheter, and for the precision mixing of liquids such as reagents, medical specimens, inks, paints and the like.
The apparatus is readily distinguishable from the prior art in that it solves the problems inherent in the precision aspiration and dispensing of large or small liquid aliquots by providing a simple, inexpensive, positive acting, and highly versatile liquid handling apparatus. Because of its simplicity, the apparatus of the present invention is easy to maintain and clean, is highly reliable in operation and can readily be operated by unskilled, non-professional personnel.